chkconfig

Erik Troan from Red Hat designed the chkconfig  utility, based on chkconfig under IRIX, a UNIX from Silicon Graphics, Inc.

chkconfig was designed to enable/disable services for automatic launch during system initialization without editing, renaming or moving init scripts.

The key idea is to add a special header in comment section that starts each init script to each init script. Presence of such header permits automatically determine on which levels the script should run and with which priorities. In other words automate handling of symbolic links for init scripts and provide useful reference as for which services are active on what levels.  In Red Hat version the header is very simple and well designed. It consists of just two lines:

• A line with "#chkconfig:" prefix that provides information about set of levels on which daemon should run and start and kill priorities that should be used.
• A line with "#description:" prefix which provide short description of the init script purpose.  

Here is an example of Red Hat chkconfig header:

#chkconfig: 2345 80 05
#description: Oracle Server

Red Hat implementation is a binary. Scripting language is a better language for writing such utilities and later Suse reimplemented it as Perl script. But in addition to providing Red Hat functionality Suse version redefined the header,  adding several additional lines. The net result is a more complex header without too much gain in functionality. Generally Suse startup scripts are so over-engineered that they can be considered a classic instance of Christmas tree syndrome ;-). Ubuntu  uses Suse version of chkconfig.  We will discuss Red Hat version only, but reference contains Suse man page just for completeness.

Syntax of Red Hat version

chkconfig --list [name]

chkconfig --add name

chkconfig --del name

chkconfig [--level levels] name 
<on|off|reset>

chkconfig [--level levels] name

• --level  levels The run levels an operation should pertain to.
  Given as a string of numbers from 0 to 7. For example, --level 35 specifies runlevels 3 and 5.
• --add  name Add a new service for management by chkconfig. When a new service is added, chkconfig ensures that the service has either a start or a kill entry in every runlevel. If any runlevel is missing such an entry, chkconfig creates the appropriate entry as specified by the default values in the init script. Note that default entries in LSB-delimited 'INIT INFO' sections take precedence over the default runlevels in the initscript.
  
• --del  name Delete the service from chkconfig management, and remove any links in /etc/rc[0-6].d which pertain to it.

  Note that future package installs for this service may run chkconfig --add, which will re-add such links.
  To disable a service, run chkconfig name off.
  

• --list  name List all of the services which chkconfig knows about, and whether they are stopped or started in each runlevel. If name is specified, information is only displayed about service name.

The chkconfig binary resides in /sbin with default permissions that allow any user to execute it, although the user without root privileges can only view the current chkconfig configuration.  So any user can get list of services running:

[root]# chkconfig --list | grep ":on"

find /etc/rc.d -name "*cron*" -ls

Modifying chkconfig Entries

Manually modifying levels on which daemon runs is a mixed blessing as it can interfere with the header of theinit script that chkconfig is using. But sometimes it is necessary. In this case the command is:

chkconfig [--level <levels>] <name> <on|off|reset>

For example, if we decide to disable crond for runlevel 2, the chkconfig --level 2 crond off command (executed by root) would turn off crond for the runlevel of 2. Running chkconfig --list will confirm that crond's configuration has been modified.

Finally, you can enable/disable a command for multiple runlevels with one chkconfig command. For example entering

chkconfig --levels 2345 crond on

Removing all symbolic links to the init script

Some people think that disabling sendmail desirable since it reduces potential security risks. To remove sendmail from chkconfig, type

chkconfig --del sendmail

In case you did not change manually level on which sendmail should start this is adential affect to

chkconfig  sendmail off

Affter both cpommand you better chack the result with  find. For example: 

[root]# find /etc/rc.d -name '*sendmail*' -print
/etc/rc.d/init.d/sendmail

Configurng new init script

Let's use the example script from Managing Initscripts with Red Hat's chkconfig Linux Journal (with some minor modifications)

#!/bin/sh

#chkconfig: 2345 80 05
#description: Oracle  Server

ORA_HOME=/usr/home/oracle/product/11.1.2
ORA_OWNER=oracle

if [ ! -f $ORA_HOME/bin/dbstart ]
then
  echo "Oracle startup: cannot start"
  exit
fi

case "$1" in
  "start")
     su - $ORA_OWNER -c $ORA_HOME/bin/dbstart
     su - $ORA_OWNER -c "$ORA_HOME/bin/lsnrctl start"
     ;;
  "stop")
     su - $ORA_OWNER -c $ORA_HOME/bin/dbshut
     su - $ORA_OWNER -c "$ORA_HOME/bin/lsnrctl stop"
     ;;
esac

Note the special header

#chkconfig: 2345 80 05
#description: Oracle  Server

It informs chkconfig on which levels and with what priority links to startup script should be created. Those to line is the minimum requirements of an initscript that can be used in conjunction with chkconfig.

These lines are needed by chkconfig to determine how to establish the initial runlevels to add the service as well as set the priority for the start-and-stop script execution order. These lines denote the script will start Oracle 8 server for the runlevels 2, 3, 4 and 5. In addition, the start priority will be set to 80 while the stop priority will be 05.

Now that the script is in place with the appropriate execute permissions and the required chkconfig comments are in place, we can add the initscript to the chkconfig configuration by typing, as root,

chkconfig --add oracle

Using chkconfig's query feature, we can verify our addition:

[root]# chkconfig --list | grep oracle
oracle        0:off     1:off   2:on   3:on   4:on   5:on  6:off

Also, we can type our standard find command to see how chkconfig set up the symbolic links:

[root]# find /etc/rc.d -name '*oracle' -print
/etc/rc.d/init.d/oracle
/etc/rc.d/rc0.d/K05oracle
/etc/rc.d/rc1.d/K05oracle
/etc/rc.d/rc2.d/S80oracle
/etc/rc.d/rc3.d/S80oracle
/etc/rc.d/rc4.d/S80oracle
/etc/rc.d/rc5.d/S80oracle
/etc/rc.d/rc6.d/K05oracle

[root]# chkconfig oracle reset
[root]# find /etc/rc.d -name '*oracle' -print
/etc/rc.d/init.d/oracle
/etc/rc.d/rc0.d/K03oracle
/etc/rc.d/rc1.d/K03oracle
/etc/rc.d/rc2.d/S80oracle
/etc/rc.d/rc3.d/S80oracle
/etc/rc.d/rc4.d/S80oracle
/etc/rc.d/rc5.d/S80oracle
/etc/rc.d/rc6.d/K03oracle

Managing of services which run from xinetd

When inetd was replaced by xinetd in Red Hat 7 chkconfig functionality has been extended to manage some of the functionality of xinetd's Internet services. Sample output is shown below:

[root]# chkconfig --list
...
xinetd based services:
      finger:  on
      linuxconf-web:  off
      rexec:  off
      rlogin:  off
      rsh:  off
      ntalk:  off
      talk:  off
      telnet:  on
      tftp:  off
      wu-ftpd:   on

To disable a xinetd feature, perhaps finger, you could type

# 
chkconfig finger off

When the configuration is changed, the xinetd is signaled automatically to reload the new configuration with the command /etc/init.d/xinetd reload, that is executed by chkconfig. This script performs a kill with the SIGUSR2 signal which instructs xinetd to perform a hard reconfiguration. the active sessions of services offered through xinetd (i.e., Telnet, FTP, etc.) were immediately terminated. That might not be a problem for you, assuming you can plan the best time to disable/enable xinetd services on your system. As an alternative, you can modify the /etc/init.d/xinetd script so that the reload option sends a SIGUSR1 signal, which is a soft reconfiguration. This will restart the services without terminating existing connections.

Adding xinetd services for chkconfig management is as simple as adding an xinetd service file into the /etc/xinetd.d directory. The chkconfig utility will automatically pick it up and make it available for management through the chkconfig utility.

NEWS CONTENTS

Old News ;-)

Updated chkconfig packages that resolve several issues with the alternatives utility and provide various man page corrections are now available.

The basic system utility chkconfig updates and queries runlevel information for system services.

These updated chkconfig packages provide fixes for the following bugs:

* when the "alternatives" utility was run and an error occurred, no contextual information such as the line number of the error was provided. With this update, upon an error, "alternatives" now provides the line number where the error occurred in the relevant file in the /var/lib/alternatives directory, which helps to diagnose alternatives-related errors. (BZ#441443)

* using the "alternatives" utility and selecting the last available option and then uninstalling the program which provided that alternative did not result in the removal of the symbolic links for that option. Because the previously-set alternative was no longer available and the symbolic link remained, the program was then rendered unusable. With this update, when the aforementioned condition is met, the "alternatives" program now recognizes that the program is no longer available and removes the extraneous symbolic link, with the result that the next-best alternative is properly selected, and running the program works as expected. (BZ#525051)

* the chkconfig(8) man page contained a description of the syntax for running chkconfig that differed from the correct description presented when running "chkconfig --help". The man page has been corrected to correspond with the program's help information. (BZ#501225)

* the chkconfig(8) man page contained an incorrect reference to runlevel 7, which does not exist (runlevels extend from 0 to 6, inclusive). This update corrects the man page by removing all references to "runlevel 7". (BZ#466740)

* the ntsysv(8) man page referenced a non-existent man page, servicesconf. This reference has been removed. (BZ#516599)

All users of chkconfig are advised to upgrade to these updated packages, which resolve these issues

Recommended Links

Softpanorama Recommended

Top articles

Sites

Chapter 1. Boot Process, Init, and Shutdown

CentOS - chkconfig Cloud Computing and Web Hosting Knowledge Center by Rackspace

Managing Initscripts with Red Hat's chkconfig Linux Journal Apr 01, 2001 By Jimmy Ball Old but still useful paper. Much of the material on this page was adapted from this article.

9.2.3. Using the chkconfig Utility (Red HAt

Reference

chkconfig(8) - Linux man page

chkconfig - updates and queries runlevel information for system services

chkconfig --list [name]
chkconfig --add name
chkconfig --del name
chkconfig [--level levels] name <on|off|reset>
chkconfig [--level levels] name

chkconfig provides a simple command-line tool for maintaining the /etc/rc[0-6].d directory hierarchy by relieving system administrators of the task of directly manipulating the numerous symbolic links in those directories.

This implementation of chkconfig was inspired by the chkconfig command present in the IRIX operating system. Rather than maintaining configuration information outside of the /etc/rc[0-6].d hierarchy, however, this version directly manages the symlinks in /etc/rc[0-6].d. This leaves all of the configuration information regarding what services init starts in a single location.

chkconfig has five distinct functions: adding new services for management, removing services from management, listing the current startup information for services, changing the startup information for services, and checking the startup state of a particular service.

When chkconfig is run without any options, it displays usage information. If only a service name is given, it checks to see if the service is configured to be started in the current runlevel. If it is, chkconfig returns true; otherwise it returns false. The --level option may be used to have chkconfig query an alternative runlevel rather than the current one.

If one of on, off, or reset is specified after the service name, chkconfig changes the startup information for the specified service. The on and off flags cause the service to be started or stopped, respectively, in the runlevels being changed. The reset flag resets the startup information for the service to whatever is specified in the init script in question.

By default, the on and off options affect only runlevels 2, 3, 4, and 5, while reset affects all of the runlevels. The --level option may be used to specify which runlevels are affected.

Note that for every service, each runlevel has either a start script or a stop script. When switching runlevels, init will not re-start an already-started service, and will not re-stop a service that is not running.

chkconfig also can manage xinetd scripts via the means of xinetd.d configuration files. Note that only the on, off, and --list commands are supported for xinetd.d services.

Options

--level levels

Specifies the run levels an operation should pertain to. It is given as a string of numbers from 0 to 7. For example, --level 35 specifies runlevels 3 and 5.

--add name

This option adds a new service for management by chkconfig. When a new service is added, chkconfig ensures that the service has either a start or a kill entry in every runlevel. If any runlevel is missing such an entry, chkconfig creates the appropriate entry as specified by the default values in the init script. Note that default entries in LSB-delimited 'INIT INFO' sections take precedence over the default runlevels in the initscript.

--del name

The service is removed from chkconfig management, and any symbolic links in /etc/rc[0-6].d which pertain to it are removed.

Note that future package installs for this service may run chkconfig --add, which will re-add such links. To disable a service, run chkconfig name off.

--list name

This option lists all of the services which chkconfig knows about, and whether they are stopped or started in each runlevel. If name is specified, information in only display about service name.

Runlevel Files

Each service which should be manageable by chkconfig needs two or more commented lines added to its init.d script. The first line tells chkconfig what runlevels the service should be started in by default, as well as the start and stop priority levels. If the service should not, by default, be started in any runlevels, a - should be used in place of the runlevels list. The second line contains a description for the service, and may be extended across multiple lines with backslash continuation.

For example, random.init has these three lines:

# chkconfig: 2345 20 80
# description: Saves and restores system entropy pool for \
#              higher quality random number generation.

This says that the random script should be started in levels 2, 3, 4, and 5, that its start priority should be 20, and that its stop priority should be 80. You should be able to figure out what the description says; the \ causes the line to be continued. The extra space in front of the line is ignored.

See Also

init(8) ntsysv(8) system-config-services(8)

Author

Erik Troan <[email protected]>

Ubuntu Manpage chkconfig - enable or disable system services

maverick (8) chkconfig.8.gz
Provided by: chkconfig_11.0-79.1-2_all

NAME

       chkconfig - enable or disable system services

SYNOPSIS

       chkconfig -t|--terse [names]
       chkconfig -s|--set [name state]
       chkconfig -e|--edit [names]
       chkconfig -c|--check name [state]
       chkconfig -l|--list [--deps] [names]
       chkconfig -A|--allservices
       chkconfig -a|--add [names]
       chkconfig -d|--del [names]

DESCRIPTION

       chkconfig  is  used  to manipulate the runlevel links at boot time (see
       init.d(7)).  It  can  be  thought  of  as  a  frontend  to  insserv(8).
       Chkconfig  can  run  in six different modes: terse list mode, set mode,
       edit mode, list mode, add mode and delete mode. The  last  three  modes
       were added for compatiblity reasons.

TERSE LIST MODE

       This  mode  lists  the  state  of  the specified services, or all known
       services if no service name was provided. Every printed  line  consists
       of  the name of the service and the runlevels the service is configured
       for at the moment. If it is configured in  no  runlevel,  off  is  used
       instead,  if  it is configured in the runlevels defined as a default by
       the start script, on is used. If the service is  an  enabled  inetd  or
       xinetd  service,  inetd  and xinetd are used. Inetd/xinetd services are
       configured in /etc/inetd.d and /etc/xinetd.d, respectively. You can use
       the  -A  or  --allservices  parameter  to  get  all  services (even the
       boot.*-services) listed.

       If chkconfig is called without arguments, all services  are  listed  in
       terse mode.

SET MODE

       Set  mode  is  used  to configure at which runlevel a service should be
       started. The arguments must be specified as pairs of service  name  and
       new  state.  You  can  use  on  and off as special states to select the
       default set of runlevels or to disable a service  completely.  You  can
       use  inetd or xinetd to configure a service managed by the inetd/xinetd
       daemons.

       If no services are  specified,  chkconfig  reads  lines  from  standard
       input.  Each  line  must  consist  of  a service/state pair. As this is
       exactly the output of  the  terse  list  mode,  this  can  be  used  to
       reconfigure a service specification saved by a former run.

       If  the  option  -f  or --force is also given, insserv is called with a
       '-f' option.

EDIT MODE

       This mode is a combination of the terse list mode  and  set  mode.   It
       writes  the  state of all specified services (or all known services, if
       no service was provided) into a temporary file, starts  an  editor  and
       re-configures  all  services  to  reflect  the  states  of  the changed
       temporary file.

CHECK MODE

       This mode can be used to check the state of a service.  chkconfig exits
       with  a  return  code  of  '0'  if the service is enabled in all of the
       specified runlevels, otherwise the exit status is '1'. If chkconfig  is
       called  with  only a service name the current runlevel of the system is
       used for checking.

LIST MODE

       List mode prints for each specified service a line that consists of the
       service  name  and for runlevels zero to six on or off depending if the
       service will be started or not.  on will be printed in bright green  if
       the output is written to a terminal. If the --deps option is given, the
       names of the services that must  be  started  before  this  service  is
       appended  to  each  line. The inetd/xinetd services are listed in extra
       sections.

       You can use the -A or --allservices parameter to get all services (even
       the boot.*-services) listed.

ADD MODE

       Calls insserv to enable a service and uses list mode to display the new
       setting afterwards.

DEL MODE

       Same as add mode, but disable the service.

OTHER OPTIONS

       When no service names are given on the command line, chkconfig defaults
       to all known services excluding those that are not enabled in runlevels
       1 to 6 and start with 'boot.'.  Use the --allservices or -A  option  if
       you want to see such services as well.

EXAMPLES

              chkconfig

       list the runlevel configuration of all known services

              chkconfig apache

       list the runlevel configuration of the apache web server

              chkconfig -t apache xntpd

       list  the  runlevel  configuration  of  the  apache  web server and the
       network time protocol daemon.

              chkconfig apache on

       configure the apache web server to be started on next boot time.

              chkconfig apache 5

       configure the apache web server  to  be  started  only  if  the  system
       reaches runlevel 5.

              chkconfig apache 35

       configure the apache web server for runlevel 3 and 5.

              chkconfig apache on xntpd off

       configure two services

              chkconfig finger xinetd

       configure a xinetd service

              chkconfig -A >~root/chkconfig.save

       backup the current configuration

              chkconfig -s <~root/chkconfig.save

       restore the configuration

              chkconfig -e apache xntpd

       change the runlevel configuration interactively

              chkconfig -e

       change the runlevel configuration of all services interactively

FILES

       /etc/init.d/
              path  to the boot script base directory as required by the Linux
              Standard Base Specification (LSB).

       /etc/inetd.d/
              path to the inetd services. See the inetd manpage  to  find  out
              how to enable this feature.

       /etc/xinetd.d/
              path to the xinetd services.

SEE ALSO

       init.d(7), init(7), inetd(8) xinetd(8) insserv(8)

COPYRIGHT

       2003 SuSE Linux AG, Nuernberg, Germany.

AUTHOR

       Michael Schroeder <[email protected]>

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Last modified: March, 12, 2019